The present invention relates to a hydraulic control system for an automotive automatic transmission and a line pressure control method.
Generally, a conventional automatic transmission includes a torque convertor, a multi-stage gear shift mechanism connected to the torque convertor, and a hydraulic control system which selects a gear stage of the gear shift mechanism according to a driving state of the vehicle.
The above hydraulic control system includes a regulator valve for regulating line pressure to be in high or low state. The regulator valve is designed so that it regulates line pressure to be in a low state only when a damper clutch is operated in third and fourth speeds. As a result, the ability to achieve low line pressure is limited such that shift efficiency deteriorates.